Necropsies on two killer whales that died after spending weeks in an Alaska river have provided no obvious reasons for why the animals died.
Veterinarians on Wednesday completed a necropsy on a second killer whale found dead in the Nushagak River.
Two adult female whales were found dead in the river on Saturday, and a third whale, a juvenile, hasn't been seen since. The necropsy on the first whale showed she was pregnant.
NOAA's National Marine Fisheries Service says over 100 samples were taken from the whales for analysis in hopes of providing a clearer picture of why they died.
The agency says it is the first time that killer whales were reported in fresh water in Alaska.